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Androstadienol (androsta-5,16-dien-3β-ol) is an endogenous C19 (nineteen-carbon) delta-5,16 steroid alcohol that functions as the committed biosynthetic precursor of the 16-androstene family of chemosensory steroids, including androstadienone, androstenone and androstenol. It is formed in the gonads (and, at lower levels, in other steroidogenic tissue) from pregnenolone by a minor side activity of the enzyme CYP17A1 (cytochrome P450 17A1, the same enzyme that makes dehydroepiandrosterone); this activity is historically called andien-beta synthase or 16-ene-synthase. Because its downstream metabolites are the putative human axillary chemosignals and the compounds responsible for boar taint, androstadienol occupies the upstream branch point of a pathway of considerable interest to olfactory neuroscience and reproductive endocrinology. It should not be confused with fasedienol (aloradine), a synthetic 4,16-dien-3β-ol nasal drug; androstadienol is the naturally occurring 5,16-diene.
- Serves as the committed biosynthetic precursor to the human putative chemosignals androstadienone and androstenol
- Functions as a biochemical marker of CYP17A1 16-ene-synthase (andien-beta synthase) activity in steroidogenic tissue
- Provides a chemically tractable steroid scaffold whose 3-acetate is the synthetic precursor to the prostate-cancer drug abiraterone
- Illuminates how cytochrome b5 redirects steroidogenesis toward 16-androstene odor compounds, informing research on boar taint and human body odor
Overview
Endogenous 16-androstene precursor steroid that sits one enzymatic step upstream of the human putative pheromones androstadienone and androstenol.
- Its 3-acetate is the immediate scaffold of abiraterone; abiraterone acetate is chemically 17-(3-pyridyl)androsta-5,16-dien-3-yl acetate, so a blockbuster prostate-cancer drug is built directly on the androstadienol skeleton.
- The enzyme that makes it, historically named andien-beta synthase, turned out not to be a separate protein but a minor side activity of CYP17A1, the very same P450 that produces dehydroepiandrosterone.
- Cytochrome b5, a tiny electron-transfer protein, acts as a molecular switch that pushes CYP17A1 toward making androstadienol and other 16-androstenes; boar testis is unusually rich in it, which is why pigs generate so much odorous 16-androstene steroid.
- Androstadienol is the very first 16-androstene formed in the body, meaning every classic pheromone-class and boar-taint steroid, from androstenone to androstenol to androstadienone, descends from it.
Mechanism
Androstadienol is a C19 steroid bearing a 3-beta hydroxyl group and two carbon-carbon double bonds, one at the 5,6 position (delta-5) and one at the 16,17 position (delta-16). Its defining biological role is positional; it is the first 16-androstene (a class of C19 steroids carrying the delta-16 double bond) produced in the steroidogenic pathway.
Biosynthesis proceeds from pregnenolone (the parent steroid made from cholesterol) through an unusual reaction in which the two-carbon acetyl side chain at position C17 is removed as acetic acid while the delta-16 double bond is introduced. This transformation was long attributed to a distinct enzyme termed andien-beta synthase, but it is now established to be a third catalytic activity of CYP17A1, the same cytochrome P450 (a heme-containing oxidase) that performs 17-alpha-hydroxylation and 17,20-lyase chemistry to make dehydroepiandrosterone.
The 16-ene-synthase reaction is strongly promoted by cytochrome b5 (a small electron-transfer hemoprotein that acts as an effector on CYP17A1); tissues and genotypes rich in cytochrome b5, such as boar testis, divert a larger fraction of pregnenolone toward 16-androstenes rather than toward conventional androgens. Once formed, androstadienol is metabolized onward; 3-beta-hydroxysteroid dehydrogenase with its associated isomerase (3beta-HSD, which oxidizes the 3-hydroxyl and shifts the double bond from delta-5 to delta-4) converts it to 4,16-androstadien-3-one (androstadienone), the musky steroid studied as a human chemosignal.
Reduction of the delta-4 bond by 5-alpha-reductase yields 5alpha-androst-16-en-3-one (androstenone), and reduction of the 3-ketone by 3-alpha or 3-beta hydroxysteroid dehydrogenases yields the alcohols 5alpha-androst-16-en-3alpha-ol and 3beta-ol (collectively androstenol). These downstream odorants, not androstadienol itself, are the ligands for the human olfactory receptor OR7D4 and drive the perceived urinous or sandalwood-like odors; androstadienol is therefore best described as a neuroactive-steroid precursor whose neurological relevance is chemosensory rather than via classical -gated ion channels.
Unlike the anesthetic and anxiolytic neurosteroids (for example allopregnanolone), androstadienol has no well-characterized direct action at the -A receptor (the brain's principal inhibitory ion channel) or the (a -gated excitatory channel); its inclusion among neurosteroids reflects its endogenous steroidogenic origin and its position at the head of a chemosignaling cascade. In synthetic chemistry the molecule and its 3-acetate are versatile scaffolds; the 3-acetate of androsta-5,16-dien-3beta-ol is the immediate precursor used to build the 17-(3-pyridyl) side chain of abiraterone, an approved inhibitor of CYP17A1 used in prostate cancer.
receptor fingerprint
CYP17A1 (16-ene-synthase / andien-beta synthase activity)Product of this catalytic activity
Cytochrome b5Cofactor that allosterically enhances its synthesis
3beta-HSD / delta-5-delta-4 isomeraseSubstrate for onward metabolism
5alpha-reductaseDownstream metabolic step
OR7D4 olfactory receptorIndirect, via odorous metabolites
Safetyrisks and cautions, not medical advice
Androstadienol is an endogenous intermediary metabolite that is not marketed, sold, or ingested as a dietary supplement, and no human toxicology, oral bioavailability, or dosing data exist for it. It circulates and is metabolized at trace levels as part of normal steroidogenesis, and it is rapidly converted by 3beta-HSD and 5alpha-reductase to its downstream products, so free tissue concentrations are low.
The principal practical consequence associated with this pathway is olfactory rather than toxicological; the downstream metabolites androstenone and androstenol contribute to human axillary body odor and, in pigs, to boar taint, the off-odor of meat from intact males. Individuals vary genetically in their ability to smell these metabolites, which is governed in part by polymorphisms in the OR7D4 olfactory receptor. No claims of therapeutic benefit or supplement safety for androstadienol itself are supported by evidence.
History
The compound was characterized in the late 1960s and early 1970s by D. B. Gower and colleagues, whose studies in boar testis established that androsta-5,16-dien-3-ol is synthesized from pregnenolone and identified the subcellular site of its formation; this line of work introduced the term andien-beta synthase for the responsible activity and traced the intermediary role of 5-pregnene-3,20-diol. Subsequent work through the 1980s, notably by Nakajin, Hall and coworkers, showed that cytochrome b5 markedly stimulates the synthesis of delta-16 C19 steroids by purified testicular cytochrome P450, foreshadowing the modern understanding of CYP17A1 regulation.
In the 1990s Gower's group extended the biosynthetic studies to human testis, and in 2003 Soucy, Lacoste and Luu-The demonstrated that this 16-ene-synthase activity is intrinsic to P450c17 (CYP17A1) itself, resolving the long-standing question of whether andien-beta synthase was a separate enzyme. Interest in the scaffold was renewed by medicinal chemistry, as androsta-5,16-dien-3beta-ol acetate became the practical starting material for abiraterone.
Reputation
Within nootropic, pheromone and body-odor communities the celebrated molecules are androstadienone and androstenol, the odorous 16-androstenes that have been marketed in fragrances and studied for effects on mood, attention and social perception. Androstadienol itself is comparatively obscure and is recognized mainly by steroid biochemists as the upstream precursor of those compounds and by synthetic chemists as an abiraterone building block. It is not a consumer product and carries no established performance or cognitive reputation of its own; its significance is mechanistic, marking the entry point into the chemosensory-steroid pathway. Care is warranted because its name closely resembles that of fasedienol (aloradine), an unrelated synthetic 4,16-diene investigated as an intranasal anxiolytic.
Subjective profileweighing the evidence above
Not something anyone takes. It is a fleeting intermediate in steroid synthesis, converted downstream almost as fast as it forms, with no oral, dosing or toxicology data and no consumer product. Useful to biochemists tracking CYP17A1 activity, and that is the entire use.
Resources
This entry is here for reference.
Research
- 1971first citedFurther studies on the biosynthesis of androsta-5,16-dien-3- -ol and the subcellular location o…
- 2023most recentSteroid 17α-hydroxylase/17, 20-lyase (cytochrome P450 17A1).
- 1.Further studies on the biosynthesis of androsta-5,16-dien-3- -ol and the subcellular location of the site of biosynthesis.
- 2.The intermediary role of 5-pregnene-3 ,20 -diol in the biosynthesis of 16-unsaturated C 19 steroids in boar testis.
- 3.Assessment of porcine and human 16-ene-synthase, a third activity of P450c17, in the formation of an androstenol precursor. Role of recombinant cytochrome b5 and P450 reductase.
- 4.Cytochrome b5 promotes the synthesis of delta 16-C19 steroids by homogeneous cytochrome P-450 C21 side-chain cleavage from pig testis.
- 5.Studies of 16-androstene steroid biosynthesis and binding in human testis.
- 6.Use of gas chromatographic-mass spectrometric techniques in studies of androst-16-ene and androgen biosynthesis in human testis; cytosolic specific binding of 5alpha-androst-16-en-3-one.
- 7.1H-indazole and 2H-indazole derivatives of androsta-5,16-dien-3beta-ol.
- 8.The role of porcine cytochrome b5A and cytochrome b5B in the regulation of cytochrome P45017A1 activities.
- 9.Characterization of 17alpha-hydroxysteroid dehydrogenase activity (17alpha-HSD) and its involvement in the biosynthesis of epitestosterone.
- 10.5α-Androst-16-en-3α-ol β-D-glucuronide, precursor of 5α-androst-16-en-3α-ol in human sweat.
- 11.Microbial pathways leading to steroidal malodour in the axilla.
- 12.Effect of mutations in porcine CYB5A and CYP17A1 on the metabolism of pregnenolone.
19 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
Is androstadienol the same as androstadienone?
No. Androstadienol is androsta-5,16-dien-3-beta-ol, an alcohol with double bonds at the 5 and 16 positions. Androstadienone is androsta-4,16-dien-3-one, a ketone with the double bond shifted to the 4 position. Androstadienol is the precursor; the enzyme 3beta-HSD converts it into androstadienone.
Is androstadienol the same as fasedienol (aloradine)?
No, and the names are easily confused. Fasedienol (aloradine) is a synthetic androsta-4,16-dien-3-beta-ol investigated as an intranasal treatment for anxiety. Androstadienol is the naturally occurring 5,16-diene precursor steroid and is not a drug.
Where in the body is it made?
It is produced mainly in the testis from pregnenolone through a side activity of CYP17A1 that removes the C17 side chain and installs the 16,17 double bond. The reaction is strongly enhanced by the cofactor cytochrome b5.
Does androstadienol act on brain receptors like other neurosteroids?
There is no well-characterized direct action at GABA-A or NMDA receptors, unlike anesthetic neurosteroids such as allopregnanolone. Its relevance to the nervous system is chemosensory; its odorous downstream metabolites activate olfactory receptors such as OR7D4.
Can you buy or take androstadienol as a supplement?
No. It is an endogenous metabolic intermediate with no supplement market, no dosing data, and no established human benefit. The odorous downstream compounds androstenone and androstenol are what appear in fragrance and pheromone products.
Limitations of the evidence
- No human supplementation or ingestion data exist; it is not a consumer product
Notes and cautions
- Its downstream metabolites androstenone and androstenol contribute to human axillary body odor
- The same metabolites are responsible for boar taint, an off-odor in pork from intact males
- Perceived odor intensity and quality of the metabolites vary widely between people due to OR7D4 olfactory receptor polymorphisms